300‐GHz integrated heterodyne receiver with carrier lock‐in Costas loop.

A carrier signal lock‐in experiment using a 300‐GHz integrated heterodyne circuit is presented. The circuit contains a single voltage‐controlled oscillator with a single set of quadrature mixers that are fabricated using 250‐nm InP double hetero‐junction bipolar transistor technology. An external feedback loop containing packaged baseband components such as amplifiers, a phase discriminator, and a filter is connected to the integrated circuit to form a complete receiver system. For a −25 dBm of input RF signal with 3.5‐GHz single‐tone carrier‐suppressed modulation, the receiver system responds with successful lock‐in range of 110 MHz centred around 311 GHz. [ABSTRACT FROM AUTHOR]